Abstract
BackgroundRadiolabeled prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) has shown superior diagnostic accuracy to conventional imaging for the detection of prostate cancer deposits . Consequently, clinical management changes have been reported in patients with biochemical recurrence (BCR) of disease after robot-assisted radical prostatectomy (RARP). We hypothesized that, due to the exclusion of patients with metastatic disease on PSMA-PET/CT, those who underwent local salvage radiation therapy (SRT) after restaging PSMA-PET/CT for BCR may have better oncological outcomes than patients who underwent “blind” SRT. ObjectiveTo compare the oncological outcome of a patient cohort that underwent PSMA-PET imaging prior to SRT with that of a patient cohort that did not have PSMA-PET imaging before SRT. Design, setting, and participantsWe included 610 patients who underwent SRT, of whom 298 underwent PSMA-PET/CT prior to SRT and 312 did not. No additional hormonal therapy was prescribed. Outcome measurements and statistical analysisTo compare both cohorts, case-control matching was performed, using the prostate-specific antigen (PSA) value at the initiation of SRT, pathological grade group, pathological T stage, surgical margin status, and biochemical persistence after RARP as matching variables. The outcome variable was biochemical progression at 1 yr after SRT, defined as either a rise of PSA ≥0.2 ng/ml above the nadir after SRT or the start of additional treatment. Results and limitationsAfter case-control matching, 216 patients were matched in both cohorts (108 patients per cohort). In the patient cohort without PSMA-PET/CT prior to SRT, of 108 patients, 23 (21%) had biochemical progression of disease at 1 yr after SRT, compared with nine (8%) who underwent restaging PSMA-PET/CT prior to SRT (p = 0.007). ConclusionsPSMA-PET/CT is found to be associated with an improved oncological outcome in patients who undergo SRT for BCR after RARP. Patient summaryPerforming prostate-specific membrane antigen positron emission tomography/computed tomography imaging in patients with biochemical recurrence of disease after robot-assisted radical prostatectomy, before initiating salvage radiation therapy, resulted in improved short-term oncological outcomes.
Highlights
In 2018, prostate cancer (PCa) accounted for 7.1% of all cancer cases, which made it the second most common type of cancer in men [1]
Stephenson et al [7] showed that in patients who did not receive androgen deprivation therapy (ADT), 55% had a prostate-specific antigen (PSA) value of 0.1 ng/ml after salvage radiation therapy (SRT). These studies showed that SRT resulted in long-term PSA-free survival in only about 50% of patients with biochemical recurrence (BCR), meaning that half of patients might not be cured by SRT alone
Patients had a median age of 67 yr (IQR 62–71) at SRT and a median PSA value at the initiation of SRT of 0.3 ng/ml (IQR 0.2–0.5)
Summary
In 2018, prostate cancer (PCa) accounted for 7.1% of all cancer cases, which made it the second most common type of cancer in men [1]. Despite good long-term outcomes of RARP, approximately 20–40% of patients experience biochemical recurrence (BCR) of disease, measured by rising prostate-specific antigen (PSA) values (ie, PSA 0.2 ng/ml) after RARP [2–4]. For these patients, salvage radiation therapy (SRT) to the prostatic fossa is the only potentially curative treatment option.
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